Police said they were on a regular narcotics patrol in the area when they spotted Legghette in the area. He was known to engage in narcotics activity and police said they approached him to talk. He immediately fled on foot which was called out by the officers over the police radio.

Bauer was sitting in his squad car nearby after completing a training session and minutes before he was due to head to a meeting at City Hall. He heard the call over the radio and pursued the suspect on foot into a stairwell at Chicago’s Thompson Center, according to police.

Police said surveillance video captured a struggle between the two inside the stairwell with the suspect pulling Bauer down the stairs. After they fell down the stairs, seven gunshots could be heard on video police obtained from the scene.

Some footage was captured by a cab driver who saw Bauer chasing Legghette on foot across the street into the Thompson Center. His cab was equipped with outward-facing video and audio, which recorded the pair. The driver pulled over and started recording video on his cellphone camera and captured the moment officers recovered the murder weapon and realized the suspect was wearing body armor.

Police said the cab driver’s video played a key role in building the case against Legghette.

Chicago Mayor Rahm Emanuel was visibly emotional while discussing Bauer’s wife, Erin, and daughter, Grace, saying, “Erin and Grace, we love you, the Bauer family, the family of CPD, 2.8 million Chicagoans, we are holding you in our hearts. We will see to it that Paul’s legacy of decency and duty lives on.”